Investigation on the fusion characterization and melting kinetics of ashes from co-firing of anthracite and pine sawdust

Co-firing of biomass and coal adds further complexity to variations in ash fusion temperature (AFT), which is regarded as a key parameter reflecting ash agglomerations. This study is focused on evaluating the ash fusion behaviour and kinetics of blends of pine sawdust (PS) and Jincheng anthracite (JC). The ash properties, ash transformation and evolution behaviours during the co-firing were determined. The AFT variations of JC/PS blends did not show a linear variation with a rising biomass ratio. The PS addition promoted the reaction of potassium with quartz to form muscovite, leading to a reduction of arcanite. As the ashing temperature was elevated, the most perceptible effect was the increasing agglomerate size due to adhesion of fine powders. For a given temperature, with a rising PS ratio, the total weight loss, maximum weight loss rate and the exothermic peak distinctly increased, and their relevant peaks shifted to a higher temperature zone. Herein, for different blends, the blending ratio of 30 wt% JC and 70 wt% PS was suggested as optimal for preventing ash-related problems. The ash fusion of blends requires less energy than pure ash at a certain temperature, which can be explained in terms of first-order-reaction with Arrhenius theory.